1. Field of the Invention
The invention relates to a pressure booster arrangement for high-pressure injection systems or high-pressure injection system pads of internal combustion engines.
2. Description of the Prior Art
One such pressure booster arrangement is the subject of the earlier German Patent Application 10 2007 021 326.5, not published before the priority date of the present application, and has a differential piston that operates with a large cross section in a medium-pressure reservoir, connected to the compression side of a pump that communicates on one side with a relatively pressureless fluid reservoir, and that is operative with partial cross sections for positive displacement in associated control and work chambers, which are separate from the medium-pressure reservoir and are disposed in a guide body that guides the differential piston in its strokes and in turn axially adjoins a valve body, and the valve body receives control and check valves for controlling communicating lines of the guide body and valve body for controllably connecting the control and work chambers with the medium-pressure reservoir or with the relatively pressureless fluid reservoir.
In operation of the pressure booster arrangement, fluid is forced into he medium-pressure reservoir by means of the pump; as a consequence, the differential piston is retracted, counter to the force of a restoring spring assembly, from a stop disposed in the medium-pressure reservoir and executes a working stroke, in which fluid is expelled from the control and work chambers and forced into a connected high-pressure storage system or into the relatively pressureless reservoir that during the working stroke is connected to the control chamber side. For the ensuing reverse stroke of the differential piston, the work and control chambers communicate with the medium-pressure reservoir, so that the restoring spring assembly returns the differential piston to the outset position again, and the fluid positively displaced by the differential piston in the medium-pressure reservoir in this reverse stroke is forced into the work and control chambers.
The guide body and the valve body have a comparatively complicated structure and should therefore be capable of being manufactured separately from one another. However, if the valve body and guide body are produced as separate segments from one another in a built guide body and valve body, it is necessary for lines of the control body and of the guide body, which lines communicate with one another at the parting plane between the segments, to be sealed off on the sides of these bodies oriented toward one another. Since the corresponding seals must at least in pat be proof against extremely high pressure and are furthermore acted upon by highly varying pressures, in other words pressure pulsations, in accordance with the succession of working and reverse strokes of the differential piston, these seals must be disposed with high sealing pressure. A further difficulty is that upon tensing of the axially joining bodies against one another that is adequate for attaining the sealing pressures, relative motions between sealing faces resting on one another parallel to the parting plane between the bodies must be prevented from occurring. It is true that the axially adjoining bodies fundamentally pin one another or in some other way are coupled together by positive engagement, in such a way that in the region of their parting plane they are hindered from relative motions parallel to the parting plane. However, if the tensing of the axially adjoining bodies is effected by the bodies of set screws embracing them, then the aforementioned pinning or positive engagement must be disproportionately large or strong, so that a satisfactory construction cannot be attained.